20A503
Moderate20A503 — Turbocharger Coolant Pump Signal Implausible
Description
What code 20A503 means
Code 20A503 means the engine control unit (DME) received a signal from the turbocharger coolant pump that doesn't match what it expects. The pump's self-diagnosis flagged the mismatch, which can point to a faulty sensor or a faulty pump.
The turbocharger coolant pump circulates coolant through the turbocharger after the engine shuts off to prevent overheating and oil coking in the turbine bearings. The DME controls the pump and monitors its operation. When it gets an implausible signal, the DME sets code 20A503.
Symptoms
Symptoms
- Possible turbocharger overheating.
- Reduced engine performance.
- A warning light on the instrument cluster.
Causes and fixes
Diagnosis and repair
- Check the turbocharger coolant pump and its wiring for damage, corrosion, or an open circuit.
- If the pump fails self-diagnosis, replace it.